Related Experiment Video
Updated: Jul 16, 2026

Process Development for the Spray-Drying of Probiotic Bacteria and Evaluation of the Product Quality
Published on: April 7, 2023
Damage of cell envelope of Lactobacillus helveticus during vacuum drying
C Santivarangkna1, M Wenning, P Foerst
1Central Institute for Food and Nutrition Research ZIEL, Section Food Process Engineering, Technische Universität München, Freising-Weihenstephan, Germany. santivar@wzw.tum.de
Aims:
The aim of this study was to gain insight into the inactivation mechanisms of Lactobacillus helveticus during vacuum drying.
Methods And Results:
Early stationary phase cells of L. helveticus were dried in a vacuum drier. Viability, cell integrity and metabolic activity of cells were assessed over time by plate counts on de Man Rogosa and Sharpe broth agar medium and cytological methods employing fluorescent reagents and nucleic acid stains. The cell envelope damage was visualized by atomic force microscopy (AFM). Fourier transform infrared spectroscopy (FT-IR) was used to indirectly observe changes in cell components during drying. Viability, metabolic activity and cell integrity decreased during vacuum drying, and different inactivation curves, characterized by the loss of ability to resume growth, and cell injuries were found. AFM images showed cracks on the surface of dried cells. Main changes in FT-IR spectra were attributed to the damage in cell envelope.
Conclusion:
The cell envelope was the main site of damage in L. helveticus during vacuum drying.
Significance And Impact Of The Study:
Inactivation mechanisms of L. helveticus during vacuum drying were partly elucidated. This information is useful for the improvement of the viability of vacuum-dried starter cultures.
More Related Videos
10:03Investigating the Detrimental Effects of Low Pressure Plasma Sterilization on the Survival of Bacillus subtilis Spores Using Live Cell Microscopy
Published on: November 30, 2017
09:07The Effect of the Application of Thyme Essential Oil on Microbial Load During Meat Drying
Published on: March 14, 2018
Related Concept Videos
Pasteurization and Food Preservation
Methods of Sterilization I: Physical Methods
Steam sterilization uses non-toxic, low-cost moist heat in the form of saturated steam under pressure, which is fast, microbicidal, and sporicidal, and quickly warms and penetrates fabrics. Autoclaves, or steam sterilizers, expose each item to direct steam contact for a predetermined time at the necessary...
Physical Methods for Controlling Microbial Growth: Temperature
Drying Shrinkage
A portion of this drying shrinkage can be reversed; if the concrete is...
Tissue Homogenization and Cell Lysis
Mechanical methods of tissue homogenization
These methods rely on applying external physical force to disrupt...
Methods of Sterilization II: Chemical Methods
Using chemical sterilization rather than heat to clean out equipment is recommended. It eradicates and removes all bacteria,...